One thing has been clarified overnight by someone who knows. Yesterday i suggested that Sweden had broken the rules with their use of the U21 rider and i quoted this rule.
" The U21 Rider must race in a minimum of 1 heat in each meeting, Final day 1 and Final day 2 will be classed as 2 meetings. If the U21 does not get nominated before the last programmed heat for his country he will automatically replace the rider in Red or White."
I now know that i misinterpreted this rule(understandably i think !) and it actually means that if a team are just about to be pushed off for the last of their programmed rides and the reserve hasn`t been used, the Race Director will step in and make the reserve go in place of the red or white(depending on their gates).